Monthly Archives: August 2014

Treating very thin conductors in HFWorks

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Today’s tip is about thin conductors in HFWorks

High frequency devices usually involve very thin conductor such as the printed traces in PCB and IC circuits. Actually even if they are not geometrically very thin, they are usually electrically so because at high frequencies, the wavelength is very small. Such thin conductors are difficult to mesh and could lead to a very large number of mesh elements. Fortunately, SolidWorks has a neat feature called split surfaces which consist of splitting a surface to one or more sub-surfaces. Hence, we recommend to not represent the thin conductors with any part or body. Simply split the upper surface of the substrate and apply the corresponding boundary condition just on the metallic split sub-surfaces. This trick minimizes the number of mesh elements considerably and gives accurate results.

Meshing air gaps

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Today’s tip is about meshing air gaps.

Air gaps are integral parts of electrical machines. However, they can represent a real challenge even for the most advanced finite element meshers. To facilitate meshing air gaps in EMS, we recommend that you construct a separate part or body for the air gap in SolidWorks or Inventor. Then you apply a tight mesh control on the air gap parts or bodies, which should be much smaller that the mesh size in the surrounding air where the mesh is usually coarse because the field tends to decay away from the device.   Hence, you can easily mesh the air gaps and achieve a good accuracy without causing a large number of mesh elements.

Reducing cogging torque

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In electric motors, the magnets of the rotor and the slots of the stator interact. This interaction results in the so called the cogging torque. It is also called detent or “no-current” torque. Generally speaking, the cogging torque is undesirable because it causes jerkiness and speed ripple, especially at low speed. It is worth mentioning that a slotless machine is cogging torque free.

There are numerous techniques to reduce the cogging torque. EMS can be instrumental in investigating such technique without the need to build prototypes. For instance, the designer can distort the stator and/or the magnets virtually in SolidWorks or Inventor and run EMS for various distortion angles and study the effect on the torque. Similarly, one can consider various current forms or play on the number of slots. The parameterization feature of EMS makes this task fast and efficient.

Motor Back EMF

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Do you know that you can accurately compute your motor Back EMF using SolidWorks, SolidWorks Motion, and EMS right inside SolidWorks?  No need to import or export any file.  Not only can you compute the Back EMF, but also numerous motor parameters such as torque, force, inductance, flux linkage, current, voltage, generated heat, eddy current, flux lines, displacement, speed, acceleration, core loss, joule loss, and more.

Low and High Frequency Electromagnetic?

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There are two major sub-domains in electromagnetics: low-frequency and high-frequency domains. Both domains are governed by Maxwell’s equations. 

The low-frequency domain includes the major part of the electromagnetic devices such as bushing, insulators, circuit breakers, power generators, transformers, electric motors, capacitors, magnetic levitation devices, synchronous machines, DC machines, permanent magnet motors, actuators, solenoids, etc.   Use EMS for these applications.

Strictly speaking, any application in which displacement currents are negligible can be classified as low-frequency. The absence of the displacement currents de-couples the electric and magnetic fields and the situation becomes static. 

The high-frequency domain includes the study of electromagnetic waves and propagation of energy through matter. It may be some times difficult to distinguish between high-frequency and low frequency. Nevertheless, we can generally say that electromagnetic fields in which the displacement currents cannot be neglected belong to the high-frequency domain. The displacement currents couple the electric and magnetic fields to each other and the situation becomes fully dynamic. Examples of devices that use high-frequency include antennas, waveguides, transmission lines, filters, couplers, dielectric resonators, etc.  Use HFWorks for these applications.

What can EMS/Electrostatic module address?

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The Electrostatic module can help study a large number of devices and address numerous insulating and conducting phenomena. Below is just a partial list:

• Avoid rapid reduction in the resistance of an electrical insulator, that can lead to a spark jumping around or through the insulator, i.e. dielectric breakdown. This phenomenon is common in high voltage and high power applications.
• Avoid the ionization of a fluid surrounding a conductor, i.e. corona effect, in some applications such as power transmission equipments, transformers, capacitors, electric motors and generators.
• Produce corona in some other applications such as the manufacturing of ozone, scrubbing particles from air in applications such as air-conditioning systems, in nitrogen laser, when removing the unwanted electric charges from the surface of aircraft in flight, and in electrostatic copying.
• Assure that a high voltage machine is properly grounded.
• Reduce the electrostatic discharge in PCB and electronic designs.
• Assure the proper actuation force in MEMS and RF-MEMS designs.
• Avoid cross talk and distortion in electronic devices.
• Assure that a charged particle follows a desired trajectory.
• Compute the capacitance matrix, i.e. self capacitance and mutual capacitance, for high-speed electronic circuits and interconnects.
• Compute the electric field, electric flux, and voltage in insulators and around conductors.

Journey of Success: EMWorks Inc. & Team Zeus

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If you go to the University of Calgary you don’t suffer from a lack of choice when it comes to Students Union clubs. There are options for everything from swing dancing to politics to Bronies. But the most interesting club in our view is one called Team Zeus. It’s only three years old but these undergrads are building an electric racing motorcycle.

“For me I’ve always been really fascinated with electric vehicles. I like the idea of being involved with a new up and coming industry… There are still huge advancements being made every year,” says Siegfried Baumann, the past president of the group.

“I feel like if I worked with regular gasoline motorcycles I could work my entire life as engineer to increase the efficiency by one percent. Whereas with electric vehicles it’s doubling every year, it’s a very exciting time.”

Baumann is a third year mechanical engineering student who just scored a yearlong internship with BMW’s electric vehicle division based mostly on his work with Team Zeus.

The group’s goal is to get their electric bike, called the Zephyr, on a racetrack this summer. It’s being built on a Suzuki GSXR 600 racing bike frame that’s been stripped down and rebuilt as an electric motorbike.

And the race they will be participating in isn’t some endurance race where we see who developed the best batteries. Like MotoGP and Formula One this is all about sexy machines going as fast as they possibly can. Team Zeus is aiming for a top speed of 160 km/h and a range of 20-30 kilometers.

The biggest difference between electric motorbikes and their gas-powered brethren is the transmission, or lack thereof.

“Most electric bikes don’t have a transmission at all they just directly connect the motor to chain so essentially so there’s no gear shifting. The torque is quite noticeable. Once you twist the throttle you go basically. It catches a lot of people by surprise the first time they ride it,” says Baumann.

The result is exhilarating: no gearshift, no pushing in the clutch and just instant power from the moment you twist the throttle.

The group got its start from watching the movie Charge. The documentary follows several teams on their way to the world’s first electric motorbike grand prix on the Isle of Man in 2009.

“We were all really inspired by this and we decided hey why we don’t do that. Our first prototype was done on a budget of a thousand dollars,” says president Christine Hughes.

“We had an old bike that didn’t work, we took out all the mechanical parts, and we had some batteries donated to us by the solar car team here. We used a motor from a washing machine essentially and put it all together and it ran that was really exciting for us.”

That old ‘82 Honda was dubbed the Mule. While it won’t win any races with a top speed of 20 km/h, the group proved it could build a working electric motorbike. If the Mule is the golf cart of electric bikes then the Zephyr is their Tesla.

The cost of the bike and getting to the race will be around $25,000 and they recently held a successful Kickstarter campaign that raised more than $4000 with the Schulich School of Engineering will partially match the funds. They’re.

They’ll be competing against groups that will spend hundreds of thousands of dollars on their bikes. But it’s not about the money or even the credits.

“It’s all extra-curricular but I think I’ve learned more from Team Zeus than from a lot of my courses,” says Hughes. “This is cutting edge, brand new technology. We’re actually getting in here with professionals who are doing the same thing and making the same mistakes we are.”

Hughes is a fourth year mechanical engineering student and she’s looking to take her Team Zeus experience and apply it to the next big up and coming industry, clean energy.

“A lot of the skills I’m learning are so transferable – How to manage your project, how to actually design something that will work. That’s been huge. And also learning on the electrical side of things I’m really interested in sustainable energy and the motors that we’re building have lots of applications. Wind turbines use the same kind of technology to generate power and I would love to get involved with wind energy or something similar,” says Hughes.

Electric motorcycles are already on the market and much like electric cars they’re marketed as sleek, sexy, environmentally friendly city runners. And advancements made on the track shouldn’t be discounted either. It’s because of F-1 racing that we have things like disc brakes and traction control. The advances made by the teams participating in these electric motorbike races in miniaturization, propulsion and battery technology could have massive knock-on effects in electric vehicles.

How EMS helped them build their electric motor:

The Zephyr will be our first official racing bike that will aim to compete in the TTXGP this August, 2014, at a race in Salt Lake City. This will be a fully race-worthy bike brimming with horsepower, torque and overall badassery.  As part of our overall mission statement, we don’t just want to put to together a few off-the-shelf components, but strive to learn and innovate, so we have taken it upon ourselves to design an in in-wheel electric motor from scratch.  As far as we know, only one other race team has taken the in-wheel-motor approach, and we feel it is a very open ended and exciting area to explore.  Using the skills we learned from building the Axel Borg Motor, we are well aware of the challenges ahead but are determined to see it through.  This will be mounted on converted gasoline bike frame.

After a lot of research and searching we finally settled on a 2004 Suzuki GSX 600.  This bike came straight from the factory as a full fledged race bike and was never intended to be street legal.  The former owner used to be a racer as well, so this bike already has a fast and furious past.  The open frame design gives a lot of flexibility with mounting our components and the lightweight aluminum construction is perfect for our needs.  We have already stripped it down and plan on selling the gasoline engine and all its components.

For our first iteration, we will be using two Agni 95-R motors coupled together, with direct chain drive.  We will be using a Kelly controller and Lithium Ion cells carrying approximately 7.5 kW hours.  Our main objective here is to make a working bike and racing, for the experience, so we can go on to our much more ambitious second generation.

The second generation will focus mostly on the development of our own in-wheel motor and a complete retooling of the batteries and controller to take advantage of this new layout.

Motor :Our aim is to build an axial flux, brushless DC, 3-phase motor.   We are exploring a lot of different avenues in terms of magnet array geometry, coil arrangement and geometry, cored vs. uncored coils and single vs. double stator designs.  Due to the nature of electric motor design, it is difficult to update with small steps, as everything is so intertwined that changing one thing changes everything else.  We basically need to research our way into a magical combination of two or three viable arrangements and then do simulations to refine from there.  Here are some concept sketches and models that have come out of our research thus far:

Some of the initial concept sketches during brainstorming of the mechanical portions of the motor.

Our first CAD model to get an idea of the rough dimensions and fits of the motor.  This design is likely, but may still change if our optimization studies find that a double stator design or cored stator design might turn to be markedly better.

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One of our many magnetic flux density studies performed potential permanent magnet arrays.  We are considering both standard arrays and Halbach arrays, which offer more challenges but some very exciting new ground in motor design.

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Dr. Edwin Nowicki : Assoc. Professor
Dept. of Electrical and Computer Eng.
Assoc. Director, CEERE
Schulich School of Engineering
University of Calgary

03/01/2013   : “Everything’s going well so far.  We’ve done a lot of tutorials and whatnot but most of us currently focused on midterms.  Hopefully next week we can start running some meaningful simulations“…

03/13/2013:  “The software has been very helpful so far, getting an idea of the linear magnetic flux density of various magnet configurations.  It is far superior in user friendliness than Ansys was.  Sadly our old club computer is rather slow at running calculations, so we are trying to do more hand calculations to narrow down our options that we need to simulate.  Overall, I’d say we’re all very happy with the software“…

04/10/2013:   “I just tried out EMWorks the other day and its seemed to work fine without asking for a new access code or anything, so everything seems to be OK“…

05/13/2014:    “Would still be delighted to co-author a White Paper………but obviously we will be putting our main focus on assembling our current off-the-shelf motorized bike for the next four months, before we resume the motor design.

08/27/2013:   “We hope we can collaborate more in the future though. Thank you for your continuous support!”

10/10/2013:   “The software has been very helpful so far, getting an idea of the linear magnetic flux density of various magnet configurations.  It is far superior in user friendliness than Ansys was. Sadly our old club computer is rather slow at running calculations, so we are trying to do more hand calculations to narrow down our options that we need to simulate. Overall, I’d say we’re all very happy with the software”.

The validation of EMS results against an Electric Motor

https://www.youtube.com/watch?v=dC4qPwrIaJs&list=UUdLjr-xHv4t6-3TPzc-1Wqw

 

Team Zeus Facebook Page

Team Zeus Website

EMS 2014 SP2.0 Release

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EMS 2014 is the seventh release of EMS as a Gold Certified add-in to SolidWorks.
This is a major new release of the software that incorporates several new features at the meshing and pre-processing, solving and post-processing levels.

Below are the new capabilities that have been added in this release to provide users with more comprehensive simulation options and a more complete set of results.

Multi-core solving: EMS now includes fully parallelized multi-core solvers that make running studies up-to 20 times faster. Multi-core solvers come standard with EMS so you don’t need to pay extra to get it.

New easy-to-use 2D plot interface

Auto-insert Air: adding an air part is now possible allowing inserting a box, sphere or cylinder that encapsulates the whole model: the inserted part will automatically include the required cavities to avoid interference.

3D Mesh Pre-processing: Visualize and analyze the 3D mesh before launching the solver. Because meshing is critical to solution accuracy and speed, EMS now provides users unparalleled mesh viewing capabilities. This powerful feature allows users to visually inspect the mesh in a clear and uncluttered manner before launching the solver. It includes probing, section viewing and iso-clipping of the 3D mesh.

Material Library: enhanced EMS built-in material library including many new non-linear materials and material loss parameters.

Parametric Analysis: The EMS Parametric Study Mode enables designers to run multiple analysis tests automatically and then investigate the results to determine the best design. This mode makes it more intuitive for EMS user to evaluate various cases and what-if scenarios.

Exclude From Analysis: this feature enable the user to exclude an existing component from the analysis solution without having to suppress the excluded component from your SolidWorks model.

Comparison of Study Results: Enhanced tabular results from different studies and different configurations can now be compared through 2D plots.